This invention relates generally to the field of fiber optic connectors used in the telecommunications industry, and more particularly to an improved ST type adapter for interconnecting the finished ends of a pair of fiber optic cables.
It is known in the art to accomplish such interconnections by means of a wide variety of coupling devices, the interconnection often being made through an opening in a wall or bulk head. A commonly used device is known in the art as a type ST adapter which couples a pair of connector plugs, each carrying the polished end of a fiber optic core. The ends of the plugs are interconnected by an adapter body or block which includes mounting means fitting an opening in the wall or bulk head. The plugs are engaged on either side of the adapter, which engagement also aligns the fibers in coaxial relation.
It is common practice to provide, at the adapter body, a means for introducing a degree of attenuation to the transmitted light signal. The most convenient means of providing such attenuation is to include means to space the abutted ends of the aligned cores a variable axial distance. It is known in the art to provide threadedly adjustable means for this purpose. It is usually more convenient to provide a selectively replaceable component which is part of the adapter body chosen from a group of such components which imparts a fixed degree of separation of the ends of the cable cores, depending upon the degree of attenuation required. Each member of such group is identified by an assigned color coding, and in each case, engagement of an attenuator barrel with the adapter body base is by means of a bayonet fitting having automatic latching means, which means is disengaged by a tool to permit disengagement.
While convenient to use, this construction, during engagement, requires a relative rotational movement between barrel and base which results in rotating the polished end surface of one of the cores relative to the other. Where the faces are in abutting contact during this movement, the faces may, in some instances, be subject to a corresponding rotational rubbing action which imparts minute circular scratches on one or both of the finished end surfaces, with accompanying reduction in light transmitting ability. Should the attenuator barrel element be removed to be replaced by another, the identical rubbing action is repeated in an opposite rotational direction.